The overall goal of this project is to combine transgenic technology with microscopy and electrophysiology to study circuitry of the mouse retina. The use of transgenic mice to generate reporter gene products that identify neurons allows a correlation of physiology and morphology in a known subset of mammalian cells. This is a powerful technique that has been applied currently to DAergic amacrine cells. Two other transgenic lines, rod bipolars and alpha ganglion cells, have also been labeled. In the previous funding period, the applicant discovered a spontaneous bursting pattern in DAergic amacrine cells. One specific aim is to fully understand the mechanisms that modulate DAergic amacrine cells. Using RT-PCR, the applicant plans to identify the receptor subunits contained in DAergic amacrine cells and then use electrophysiological experiments to describe transmitter currents. Ultrastructural immunocytochemistry will be used to localize receptor subunits on the surface of DAergic amacrine cells. The second specific aim is to expand these approaches to other neurons in the retina. cDNA libraries will be generated from specific cell types using RT-PCR and reporter genes for cell identification. The applicant plans to characterize these neurons either in the intact retina or the retinal slice. In the continuing development of this specific aim, the applicant plans to generate new lines of transgenic animals in which different populations of neurons are labeled.